Understanding Impulsiveness in Adolescent Behaviour

A new study suggests that differences in brain wiring make some teenagers more likely to engage in addictive behavior, reported The Telegraph.

The findings, published Sunday in Nature Neuroscience, are based off brain scans of 1,896 14-year-olds -- a huge project the Toronto Sun described as "the largest imaging study of the human brain ever conducted."

Researchers found that different networks of neurons are linked to drug use, shedding new light on a longstanding debate over whether certain impulsive brain patterns are created by drug use or pre-date substance use, said The Telegraph.

Study co-author Robert Whelan of the University of Vermont told the Toronto Sun that lower activity detected in the part of the brain tied to experimental behavior in adolescence makes some young people more likely to respond impulsively, explaining, that their "networks are not working as well." _GlobalPost

Impulsive behaviours can manifest at any age, but adolescence is a particular time when volatility and impulsiveness are observed. Interestingly, not all teenagers are equally caught up in the tumult of the stormy teens, with all the risk-taking and apparent dysfunctional and self-destructive behaviour. Not all teens smoke, drink, and use drugs. Not all teen girls get pregnant, and not all teen boys set out on a life of violent or criminal behaviours.

These differences between the extent and type of impulsive behaviours in adolescents suggests that different sets of neuronal network activity are taking place inside the brains of different individual adolescents. A recent large scale international study set out to understand some of these adolescent brain differences in impulsiveness.

Newly discovered networks in the brain, shown here in color, go a long way toward explaining why some teenagers are more likely to start experimenting with drugs and alcohol. Diminished activity in some of these networks, discovered by two scientists at the University of Vermont and their European colleagues, makes some teens more impulsive -- and less able to inhibit urges to try alcohol, cigarettes and illegal drugs in early adolescence. Credit: Robert Whelan, University of Vermont, Nature Neuroscience, 2012

Robert Whelan and Hugh Garavan of the University of Vermont, along with a large group of international colleagues, report that differences in these networks provide strong evidence that some teenagers are at higher risk for drug and alcohol experimentation—simply because their brains work differently, making them more impulsive.

Their findings are presented in the journal Nature Neuroscience, published online April 29, 2012.

This discovery helps answer a long-standing chicken-or-egg question about whether certain brain patterns come before drug use—or are caused by it. "The differences in these networks seem to precede drug use," says Garavan, Whelan's colleague in UVM's psychiatry department, who also served as the principal investigator of the Irish component of a large European research project, called IMAGEN, that gathered the data about the teens in the new study.

In a key finding, diminished activity in a network involving the "orbitofrontal cortex" is associated with experimentation with alcohol, cigarettes and illegal drugs in early adolescence.

"These networks are not working as well for some kids as for others," says Whelan, making them more impulsive. Faced with a choice about smoking or drinking, the 14-year-old with a less functional impulse-regulating network will be more likely to say, "yeah, gimme, gimme, gimme!" says Garavan, "and this other kid is saying, 'no, I'm not going to do that.'"

Testing for lower function in this and other brain networks could, perhaps, be used by researchers someday as "a risk factor or biomarker for potential drug use," Garavan says.

The researchers were also able to show that other newly discovered networks are connected with the symptoms of attention-deficit hyperactivity disorder. These ADHD networks are distinct from those associated with early drug use.

...The impulsivity networks—connected areas of activity in the brain revealed by increased blood flow—begin to paint a more nuanced portrait of the neurobiology underlying the patchwork of attributes and behaviors that psychologists call impulsivity—as well as the capacity to put brakes on these impulses, a set of skills sometimes called inhibitory control.

Edythe London, Professor of Addiction Studies and Director of the UCLA Laboratory of Molecular Pharmacology, who was not part of the new study, described it as "outstanding," noting that the work by Whelan and others "substantially advances our understanding of the neural circuitry that governs inhibitory control in the adolescent brain."

Using a complex mathematical approach called factor analysis, Whelan and colleagues were able to fish out seven networks involved when impulses were successfully inhibited and six networks involved when inhibition failed—from the vast and chaotic actions of a teenage brain at work. These networks "light up," Whelan says, in a functional MRI scanner during trials when the teenagers were asked to perform a repetitive task that involved pushing a button on a keyboard, but then were able to successfully stop—or inhibit—the act of pushing the button in mid-action. Those teens with better inhibitory control were able to succeed at this task faster._MedicalXpress

Nature Neuroscience Abstract and Figures

The adolescent brain is in transition between childhood and adulthood, and clearly has not matured fully. But not all adolescents mature at the same rate, or to the same extent. It is important to keep these differences in mind when participating in the training or education of adolescents or post-adolescents.

Modern practises of education and child raising -- combined with an Idiocratogenic popular culture -- combine to create a perfect storm of lifelong quasi-adolescent incompetence in far too many young people whose parents are unable or unwilling to assist their development. As a result, entire generations are overloaded by too many cohorts with poorly developed executive function, life perspective, self-control, or rationally directed creativity and wisdom.

Perhaps the saddest thing of all, is that modern political leadership is more likely to be interested in how it can use the findings of research such as that above, to manipulate future voters to keep them in power, rather than wanting to develop ways to strengthen the self-control, independent judgment, productive initiative, and functional imaginations of its youth.